A category of endeavor in which one is highly skilled, well prepared, or blessed with natural talent and, therefore, enjoys a high liklihood of success.

From card games relying on making or ditching books or tricks, such as Hearts or Spades. In a making game, for example, if you are holding all or most of the desired cards in a given suit (hearts, spades, diamonds, clubs) then you can be fairly sure of taking a high number of 'books' or plays.

I'm going to need some help getting ready for this test... Math's really not my strong suit.

Get Melanie to talk to her for you... Diplomacy's always been her strong suit.

A term derived from card games in which, because of defined superiority or dealt strength, certain card suits become more powerful during a card game. Usually used as metaphor to decribe dominant or distinctive qualities of a person, place or thing.

He went to Hooters for the food? That's not exactly their strong suit LOL.